This invention relates to a method of saving operating data of a controller of a network element as set forth in the preamble of claim 1, and to a controller for a network element as set forth in the preamble of claim 9.
Network elements are facilities of a communications network which serve, for example, to establish connections within the network, provide access to the network, switch connections in the network, or change the format of messages which are transmitted in the network. In a communications network based on the synchronous digital hierarchy (SDH) or in a synchronous optical network (SONET), network elements include crossconnects, add/drop multiplexers, and line multiplexers.
Such network elements contain a controller for controlling and monitoring network-element-specific functions. In an article by S. Colombo et al, xe2x80x9cTechnologie der SDH-Netzelements: die Software-Plattformxe2x80x9d, Elektrisches Nachrichtenwesen, 4th Quarter 1993, pp. 322-328, it is described that network elements operate and are controlled in accordance with an object-oriented specification which has been defined by international standards committees such as CCITT (now ITU-T), ETSI, or ANSI. Functions of the network elements are described and implemented in the form of managed objects (MO).
Managed objects are real life imagesxe2x80x94and thus descriptions of static and dynamic propertiesxe2x80x94of physical or virtual components (resources) of the managed network element. In CCITT Recommendation X.720 (01/92), a managed object is defined as an abstraction of data processing and data communications resources (e.g., protocol state machines, connections, and modems) for the purposes of management.
The controller of a network element, according to the above article by S. Colombo et al, contains a CPU, a memory, and a permanent (xe2x80x9cpersistentxe2x80x9d) storage. The memory contains a number of managed objects, which are saved in the permanent storage. The saving of the managed objects in the permanent storage is slow and, because of the large number of managed objects in the memory, results in a bottleneck.
It is an object of the invention to provide a method of saving operating data of a network element which is faster than prior-art saving methods. Another object is to provide a network element controller which is suitable for carrying out the method.
These objects are attained by the features of claim 1 and claim 9, respectively. Further advantageous aspects of the invention are defined in the dependent claims.
One advantage of the invention is that it ensures consistency of the data saved in the nonvolatile storage. After receipt of a commit, any change to a managed object is saved in the nonvolatile storage, thus ensuring that the nonvolatile storage always contains a consistent backup copy of the data from the memory. Thus, after a system crash, the last valid state can be restored.
Advantageously, the nonvolatile storage is structured as a database. This reduces the amount of data to be saved and the data can be retrieved more quickly.